Fabric and method for forming pipe reinforcement

ABSTRACT

Method and fabric for forming cages for reinforcing concrete pipe, the fabric including corrugated circumferential defining strands at the female or bell-forming end thereof. The corrugated and non-corrugated circumferential strands are joined to longitudinal defining strands. Tie rods or anchors rigidly join and interconnect the separate corrugated circumferential defining strands intermediate the longitudinal defining strands. The fabric is formed into a generally cylindrical cage, the bell end is expanded outwardly, and the formed cage is cast in concrete. The tie rods embedded in the concrete resist forces of tension which would tend to further elongate and straighten the corrugated circumferential strands.

Unite States Patent [1 1 Tolliver 1 Oct. 15, 1974 [75] Inventor: Wilbur E. Tolliver, Holland, Mich.

[73] Assignee: New York Wire Mills C0rp.,

Tonawanda, NY.

22 Filed: Feb. 8, 1973 21 Appl. No.: 330,609

[52] US. Cl. 245/1, 138/175 [51] Int. Cl. ..l F161 9/08 [58] Field of Search 245/1-5; 52/653, 669, 6-70, 671, 672, 645; 138/174, 175, 176

[56] References Cited UNITED STATES PATENTS 3,034,536 5/1962 Kennisorl 138/176 3,578,036 5/1971 Francois 140/112 FOREIGN PATENTS OR APPLICATIONS 1,241,091 8/1960 France 52/669 Primary Examiner-Richard J. Herbst Attorney, Agent, or FirmPrice, Heneveld, Huizenga & Cooper [5 7 1 ABSTRACT Method and fabric for forming cages for reinforcing concrete pipe, the fabric including corrugated circumferential defining strands at the female or bell-forming end thereof. The corrugated and non-corrugated circumferential strands are joined to longitudinal defining strands. Tie rods or anchors rigidly join and interconnect the separate corrugated circumferential defining strands intermediate the longitudinal defining strands. The fabric is formed into a generally cylindrical cage, the bell end is expanded outwardly, and the formed cage is cast in concrete. The tie rods embedded in the concrete resist forces of tension which would tend to further elongate and straighten the corrugated circumferential strands.

13 Claims, 6 Drawing Figures BACKGROUND OF THE INVENTION The present invention relates to wire fabric for reinforcing concrete pipe. Such fabric normally is a network of wire strands. When rolled into a cylindrical cage, the wire strands extending the length of the cage are usually called longitudinals and those encircling the cage are called circumferentials. Some refer to the iongitudinal wires as weft wires and the circumferential wires as warp wires.

The reinforcing cages are formed either circularly or elliptically with one enlarged end. The enlarged end is called the bell end of the fabric. When the cage is formed and cast in cement, the enlarged or bell end receives the non-enlarged or spigot end of a succeeding pipe.

One technique for forming the bell end in a wire cage involves the use of non-rectilinear, for example, corrugated, circumferential strands at the bell end of the fabric. After the cage is formed, the corrugated strands are expanded radially outwardly. They straighten to some extent and thereby form the enlarged bell end.

One possible drawback to this method is that when stress forces are placed on the pipe, the corrugations or non-rectilinear deformations tend to straighten still further thereby allowing the concrete to crack. When the pipe is buried in the ground, the weight of dirt compressing the pipe tends to force the bell end to stretch outwardly to either side. The resulting forces of tension on the corrugated circumferentials tend to straighten them and thereby cause the concrete to crack.

SUMMARY OF THE INVENTION The fabric of the present invention employs nonrectilinear circumferentials, which can be expanded to form a bell, but which resist further expansion once cast in concrete. The plurality of non-rectilinear circumferential defining strands at the bell-forming end of the fabric of the present invention are rigidly interconnected by tying means positioned intermediate adjacent longitudinal defining strands. The fabric is formed into a generally cylindrical cage and the bell end is expanded radially outwardly. The tying means in no way interfere with expansion at this point, but when the cage is cast in concrete, the embedded tying means act as anchors to resist further straightening of the nonrectilinear circumferentials. Preferably, the circumferentials are regualarly corrugated and a tie rod is used to join corresponding nodes of the circumferentials which are not already joined by longitudinals. This minimizes the degree of curvature between points at which the corrugated circumferentials are anchored and thereby minimizes the extent to which the corrugated circumferentials can be straightened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of fabric manufactured in accordance with the present invention;

FIG. 2 is a plan view of an alternative embodiment fabricmanufactured in accordance with the present in vention;

FIG. 3 is a plan view of another alternative embodiment fabric manufactured in accordance with the present invention;

FIG. 4 is a perspective view of a cage formed in accordance with the present invention utilizing the fabric of FIG. 1;

. FIG. 5 is a schematic view showing stress forces on a piece of corrugated wire embedded in concrete; and

FIG. 6 is a schematic view showing stress forces on tied corrugations embedded in concrete.

PREFERRED EMBODIMENT In the preferred embodiment, the fabric 1 for forming into a cage 10 includes a plurality of rigidlyfinterconnected longitudinal defining strands 20 and circumferential defining strands 30 (FIGS. 1 and 4). At the end of fabric 1 which will become bell II in cage 10, the circumferential defining strands are non-rectilinear strands 40. The non-rectilinear circumferential defining strands 40 are connected to longitudinal defining strands 20 and are rigidly interconnected intermediate longitudinal defining strands 20 by tie rods 50 which act as anchors to prevent further straightening of nonrectilinear circumferentials 40 after cage 10 is embedded in concrete 60 (FIG. 6).

The longitudinal defining strands 20 and circumferential defining strands 30 of fabric 1 are of a material suitable for reinforcing cages 10. The accepted standard for this purpose is steel wire. Strands 20 and 30 are rigidly joined together to form a crisscross network of strands. In the case of wire strands, this joining is achieved by welding.

The circumferentials at the bell-forming end of fabric 1 are non-rectilinear strands 40. Strands 40 are of the same material as strands 20 and 30, but are deformed in a non-rectilinear fashion. The deformations preferably comprise a plurality of regularly spaced corrugations or nodes 41. When fabric is formed into a cylindrical cage 10 (FIG. 4), non-rectilinear circumferentials 40 are expanded radially outwardly. This straightens non-rectilinear strands 40 in a longitudinal direction, thereby increasing their effective length and allowing one to form a bell 11 having a greater diameter than the body of cage 10.

In another sense, the non-rectilinear strands 40 are longitudinally expandable, since they are effectively lengthened along their own longitudinal axis. The term longitudinally expandable as used herein refers to the capability of these strands to the expanded sufficiently readily and to a sufficient degree to make possible the formation of an enlarged bell end on the cylindrical cage. Naturally any strand of wire is to some extent longitudinally expandable" in the strictest interpretation of this term. However, one skilled in the art will appreciate that the term as used herein requires that the strand be capable of being expanded longitudinally on itself a sufficient degree to facilitate bell formation. Ordinary circumferential strands 30 are of a type of steel which is capable of only a slight amount of stretching so that circumferential strands 30 are not longitudinally expandable as that term is used herein.

To prevent further straightening of non-rectilinear circumferentials 40 after cage 10 is embedded in concrete, at least one tie rod 50 is used to rigidly interconnect the non-rectilinear circumferential defining strands 40 intermediate adjacent longitudinal defining strands 20 (FIG. 1). It is important that the interconnection between tie rods 50 and non-rectilinear strands 40 be over a minimized area, preferably approaching point contact, such that the ability of non-rectilinear strands 40 to be straightened is not impeded at the time bell end 11 is expanded. This is achieved by making tie rods 50 of steel rod and welding this steel rod to nonrectilinear strands 40. Tie rods 50 must be sufficiently rigid that they tend to resist bending themselves once they are embedded in concrete 60. Under some circumstances, it might be possible to use separate tie rods 50 for such longitudinally expandable strand 40 without actually interconnecting adjacent strands. Tie rods 50 would still serve as anchors, tying a strand 40 into the concrete and resisting further straightening. However, it is much better to tie adjacent strands 40 together.

Preferably, a tie rod 50 is provided for joining each corresponding node or corrugation 41 of nonrectilinear circumferential 40. In FIG. 1, nonrectilinear strands 40 have only one corrugation be tween adjacent longitudinal defining strands 20, and therefore only one tie rod 50 is required for joining corresponding nodes 41 together. In FIG. 3, there are three non-rectilinear circumferential defining strands 40 at the bell end of fabric 1. Each non-rectilinear strand 40 includes two corrugations or nodes between adjacent longitudinal defining strands 20. Thus, two tie rods 50 rigidly interconnect all three non-rectilinear circumferentials 40 intermediate a given adjacent pair of longitudinal defining strands 20. Each tie rod 50 joins the three corresponding nodes 41 of the three non-rectilinear strands 40.

Under some circumstances, it may be possible to rigidly interconnect less than all sets of corresponding nodes 41. Thus, the fabric 1 shown in FIG. 2 includes two non-rectilinear circumferential defining strands 40 at the bell forming end thereof, each having three nodes' 41 between adjacent longitudinal defining strands 20,'but only one tie rod 50 joining adjacent non-rectilinear strands 40 between adjacent longitudinal defining strands 20. Each tie rod 50 joins the corresponding middle ones of each set of three corresponding nodes 41.

To form a reinforcing cage, fabric 1 is first formed into a generally cylindrical cage 10 and the free ends of each circumferential defining strand 30 or nonrectilinear circumferential defining strand 40 are joined together in a conventional manner, by welding or the like. The bell end 11 ofcage I is then expanded radially outwardly, the radial expanding force tending to straighten each non-rectilinear circumferential defining strand 40. Once bell 11 is formed, the entire cage is placed in a casting apparatus and concrete or other equivalent material is cast therearound. While such reinforcing cages are conventionally used in conjunction with concrete, it is conceivable that synthetic organic plastic materials or other equivalent materials might be employed.

Once concrete or other material is cast around cage 10 and solidified, tie rods 50 act as anchors to prevent or minimize further straightening of non-rectilinear circumferentials 40. FIG. 5 illustrates the forces placed on a non-rectilinear circumferential 40, which does not include tie rods 50, when the pipe is placed in the ground and covered with dirt. Compressive forces on the top of the pipe result in the application of a tension force on all of the pipe circumferentials, particularly at the crown and invert of the pipe. This tension force is tendency for the concrete to crack around non-.

rectilinear circumferentials 40.

Tie rods tend to resist such forces. In FIG. 6, the forces A are resisted by tie rods 50, the resisting forces being generally indicated by arrows C. By joining all corresponding nodes or corrugations 41 which are not otherwise joined by longitudinal defining strands 20, one decreases the degree of non-rectilinearity between adjacent points on non-rectilinear strands 40 which are anchored. In fabric 1 shown in FIG. 1, for example, there is less curvature between tie rod 50 and adjacent longitudinal 20, the two anchored points, than there would be merely between two adjacent longitudinals 20. Thus, the tendency of concrete to crack under the non-rectilinear circumferential defining strands 40 is minimized.

Of course, it is understood that the above is merely a preferred embodiment of the invention and that various changes and alterations can be made without departing from the broader aspects and spirit of the invention.

Theembodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Fabric for forming reinforcing cages for pipe, such cages including a plurality of longitudinal strands, a plurality of circumferential strands and a enlarged bell end, said fabric comprising:

a plurality of longitudinal defining strands of material suitable for pipe reinforcing cages joined to a plurality of circumferential defining strands of material suitable for forming reinforcing cages;

at least a pair of circumferential defining strands at the bell forming end of said fabric being nonrectilinear;

tie means, which are shorter in length than said longitudinal defining strands, rigidly interconnecting only said non-rectilinear circumferential defining strands between each adjacent pair of longitudinal defining strands.

2. The fabric of claim 1 in which each of said nonrectilinear circumferential defining strands is regularly corrugated, said tying means joining at least one corresponding set of corrugations intermediate each adjacent pair of longitudinal defining strands.

3. The fabric of claim 2 in which said tying means comprises a tie rod'rigidly joining said corresponding corrugations.

4. The fabric of claim 3 in which one of said tie rods rigidly interconnects each corresponding set of corrugations in said non-rectilinear circumferential defining strands.

5. The fabric of claim 1 is which said tying means comprises a generally rigid tie rod joining said nonrectilinear circumferential defining strands.

6. Fabric for forming reinforcing cages for pipe, such cages including a plurality of longitudinal strands, a plurality of circumferential strands and an enlarged female end, said fabric comprising:

a plurality of longitudinal defining strands, of material suitable for pipe reinforcing cages, joined to a plurality of circumferential defining strands, of material suitable for forming reinforcing cages;

at least a pair of circumferential defining strands at the female end forming a portion of said fabric being longitudinally expandable;

tie means, which are shorter in length than said longitudinal defining strands, rigidly interconnecting only said longitudinally expandable circumferential defining strands between each adjacent pair of iongitudinal defining strands.

7. The fabric of claim 6 in which said tying means comprises a plurality of tie rods joining adjacent longitudinally expandable strands.

8. Fabric for reinforcing cages for pipe, such cages including a plurality of longitudinal strands, a plurality of circumferential strands and an enlarged female end, said fabric comprising:

a plurality of longitudinal defining strands, of material suitable for pipe reinforcing cages, joined to a plurality of circumferential defining strands, of material suitable for forming reinforcing cages;

at least one of said circumferential defining strands at the female end forming portion of said fabric being longitudinally expandable;

anchor means, which are shorter in length than said longitudinal defining strands, joined only to said longitudinally expandable circumferential defining strands between each adjacent pair of longitudinal defining strands.

9. The fabric of claim 8 in which said longitudinally expandable strand is non-rectilinear in configuration.

10. The fabric of claim 9 in which said anchor means comprises a plurality of short rods, at least one such rod being interposed between each adjacent pair of longitudinal defining strands.

11. The fabric of claim 8 in which said anchor means comprises a plurality of short rods, at least one such rod being interposed between each adjacent pair on longitudinal defining strands.

12. The fabric of claim 1 in which said nonrectilinear strands are corrogated, having corresponding nodes; said tie means comprising a plurality of tie rods, each joining one of said non-rectilinear defining strands to the other at a corresponding set of said nodes.

13. The fabric of claim 9 in which said nonrectilinear longitudinally expandable strand is corrogated, having a series of nodes, said tie means comprising a plurality of short rods, each being joined to said non-rectilinear longitudinally expandable strand at one of said nodes. 

1. Fabric for forming reinforcing cages for pipe, such cages including a plurality of longitudinal strands, a plurality of circumferential strands and a enlarged bell end, said fabric comprising: a plurality of longitudinal defining strands of material suitable for pipe reinforcing cages joined to a plurality of circumferential defining strands of material suitable for forming reinforcing cages; at least a pair of circumferential defining strands at the bell forming end of said fabric being non-rectilinear; tie means, which are shorter in length than said longitudinal defining strands, rigidly interconnecting only said nonrectilinear circumferential defining strands between each adjacent pair of longitudinal defining strands.
 2. The fabric of claim 1 in which each of said non-rectilinear circumferential defining strands is regularly corrugated, said tying means joining at least one corresponding set of corrugations intermediate each adjacent pair of longitudinal defining strands.
 3. The fabric of claim 2 in which said tying means comprises a tie rod rigidly joining said corresponding corrugations.
 4. The fabric of claim 3 in which one of said tie rods rigidly interconnects each corresponding set of corrugations in said non-rectilinear circumferential defining strands.
 5. The fabric of claim 1 is which said tying means comprises a generally rigid tie rod joining said non-rectilinear circumferential defining strands.
 6. Fabric for forming reinforcing cages for pipe, such cages including a plurality of longitudinal strands, a plurality of circumferential strands and an enlarged female end, said fabric comprising: a plurality of longitudinal defining strands, of material suitable for pipe reinforcing cages, joined to a plurality of circumferential defining strands, of material suitable for forming reinforcing cages; at least a pair of circumferential defining strands at the female end forming a portion of said fabric being longitudinally expandable; tie means, which are shorter in length than said longitudinal defining strands, rigidly interconnecting only said longitudinally expandable circumferential defining strands between each adjacent pair of longitudinal defining strands.
 7. The fabric of claim 6 in which said tying means comprises a plurality of tie rods joining adjacent longitudinally expandable strands.
 8. Fabric for reinforcing cages for pipe, such cages including a plurality of longitudinal strands, a plurality of circumferential strands and an enlarged female end, said fabric comprising: a plurality of longitudinal defining strands, of material suitable for pipe reinforcing cages, joined to a plurality of circumferential defining strands, of material suitable for forming reinforcing cages; at least one of said circumferential defining strands at the female end forming portion of said fabric being longitudinally expandable; anchor means, which are shorter in length than said longitudinal defining strands, joined only to said longitudinally expandable circumferential defining strands between each adjacent pair of longitudinal defining strands.
 9. The fabric of claim 8 in which said longitudinally expandable strand is non-rectilinear in configuration.
 10. The fabric of claim 9 in which said anchor means comprises a plurality of short rods, at least one such rod being interposed Between each adjacent pair of longitudinal defining strands.
 11. The fabric of claim 8 in which said anchor means comprises a plurality of short rods, at least one such rod being interposed between each adjacent pair on longitudinal defining strands.
 12. The fabric of claim 1 in which said non-rectilinear strands are corrogated, having corresponding nodes; said tie means comprising a plurality of tie rods, each joining one of said non-rectilinear defining strands to the other at a corresponding set of said nodes.
 13. The fabric of claim 9 in which said non-rectilinear longitudinally expandable strand is corrogated, having a series of nodes, said tie means comprising a plurality of short rods, each being joined to said non-rectilinear longitudinally expandable strand at one of said nodes. 